Skills

The Caoliao A2A service exposes three skills, all read-only.

Skill	Question it answers	Artifact name
get_entity	What is this code?	entity
get_records	What has happened to this thing?	records
list_actions	What can be done right now?	actions

Note: examples on this page come from a public demo code; they are abridged and personal names have been replaced. The live service returns field values in Chinese — the examples here are translated for illustration. The full structure is defined by schema.json.

Selecting a skill

Include a DataPart in the message parts:

{
  "kind": "data",
  "data": {
    "skill": "get_records",
    "url": "https://qr71.cn/okDISU/qssTnoy",
    "size": 10,
    "pageToken": ""
  }
}

Field	Required	Description
url	Yes	Caoliao code link
skill	No	Skill id. Defaults to get_entity
size	No	get_records only — page size, default 20, maximum 50
pageToken	No	get_records only — paging cursor

You can also send plain text; the service extracts the first code link and defaults to get_entity. Text is the fallback path. When you know which skill you want, use a DataPart — Caoliao does not perform natural-language intent recognition, that is the calling agent's job.

get_entity

Returns the whole entity in one call: name, type, owning organization, properties, current states, plus a preview of available actions and recent records.

Start here once you have a code.

Example questions (declared in the Agent Card to help callers choose):

• What equipment does this QR code refer to?
• Show me this code's name, current status and properties

Structured payload — an ObjectCard v2, the same structure returned by Public MCP's entity_get. Its main blocks:

Block	Content
thing / code / binding	Identity triple: the thing, the code, the binding between them
properties	Property fields
relations	Relation slots: located in, belongs to, responsible by, part of
states	Business states
records	Record ledger preview: total count plus the most recent entries
media	Images and attachments
actions	Available actions with their contract annotations
plans	Recurring plans
endpoints	Where this entity is reachable over Public MCP and A2A
contract	The boundaries this response honors

Top-level blocks are always present: when untracked they hold null, {} or [], all of which read as "not tracked". "Absence" semantics apply to optional sub-fields inside blocks; see "Three things consumers must know" below. Field details in Public MCP · Tools.

get_records

Returns the full ledger — inspections, repairs, maintenance — newest first, cursor-paginated. Every entry carries a snapshot of the code and thing at the time the record was created.

get_entity only previews the latest few; use this for full history.

Example questions:

• What inspections has this code had recently?
• Show me this machine's operation history

Structured payload:

{
  "url": "https://qr71.cn/okDISU/qssTnoy",
  "records": [
    {
      "id": "rec_460807516",
      "type": "inspection",
      "label": "Inspection form",
      "at": "2026-06-23T02:26:36.000Z",
      "result": "pass",
      "resultLabel": "Normal",
      "summary": "Inspection result: normal",
      "by": { "name": "Zhang" },
      "snapshot": { "codeId": "qssTnoy", "thingId": "thg_qssTnoy" }
    }
  ],
  "hasMore": false,
  "total": 1
}

When hasMore is true, the response also carries a top-level nextPageToken field; pass it as pageToken on the next call.

list_actions

Lists the actions available right now — which forms can be filled in, which state changes exist. Listing only, never execution.

Example questions:

• Which forms can be filled in on this code right now?
• What actions are available on this code?

Structured payload:

{
  "url": "https://qr71.cn/okDISU/qssTnoy",
  "actions": [
    {
      "action": "record:1556557",
      "label": "Inspection form",
      "requiresAuth": true,
      "annotations": {
        "readonly": false,
        "destructive": false,
        "idempotent": "by_request_key",
        "confirm": "none"
      },
      "precondition": null,
      "formSchemaVia": "entity_action_get",
      "humanUrl": "https://qr71.cn/okDISU/qssTnoy"
    },
    {
      "action": "record:1556556",
      "label": "Maintenance record",
      "requiresAuth": true,
      "annotations": {
        "readonly": false,
        "destructive": false,
        "idempotent": "by_request_key",
        "confirm": "none"
      },
      "precondition": null,
      "formSchemaVia": "entity_action_get",
      "humanUrl": "https://qr71.cn/okDISU/qssTnoy"
    }
  ]
}

Important: requiresAuth: true means "executing this action requires authorization". But this service never executes an action, authorized or not. The correct path is to hand humanUrl to a person, who completes the form on the scan page.

The entity_action_get named in formSchemaVia is a tool of Public MCP. A2A exposes three skills and fetching field schemas is not among them — use Public MCP when you need form fields.

annotations describe how the action will behave when it is eventually executed. They are not a description of current behavior.

Three things consumers must know

These come from the read-only contract extension and directly affect how you handle responses:

1. Neither absence nor emptiness is negation. A missing sub-field, or a block holding null / {} / [], means the platform does not track that value or cannot resolve it into a structured reference. It does not mean false or "does not exist". Caoliao would rather give nothing than pass text off as a structured reference.
2. thing.id is a transitional identifier (idScheme: "code-derived"). Do not persist a dependency on it. The stable identifier to store is code.uri.
3. Ledger entries can currently be edited by the owning organization. An immutable ledger is the target state; this contract does not promise immutability today.

Full contract at https://a2a.objqr.com/ext/caoliao-entity/v2; machine-readable schema at schema.json under the same path.

Next

• Task and Response — the full envelope you get back